What is the recommended treatment for a patient with FIGO stage IA high‑grade serous carcinoma of the ovary?

Treatment of FIGO Stage IA High-Grade Serous Ovarian Carcinoma

For FIGO stage IA high-grade serous carcinoma of the ovary, complete surgical staging followed by adjuvant platinum-based chemotherapy for 6 cycles is strongly recommended 1, 2.

Surgical Management

Complete surgical staging is mandatory and must include:

• Total abdominal hysterectomy and bilateral salpingo-oophorectomy
• Omentectomy
• Systematic pelvic and para-aortic lymphadenectomy
• Peritoneal biopsies (diaphragm, paracolic gutters, pelvic peritoneum)
• Peritoneal washings for cytology

1, 2

Critical distinction: High-grade serous carcinoma behaves fundamentally differently from low-grade disease. While low-grade serous stage IA does not require adjuvant chemotherapy after complete staging 2, high-grade serous histology mandates systemic treatment even at stage IA.

Adjuvant Chemotherapy

Regimen Options

Two acceptable platinum-based regimens exist 1, 2:

1. Carboplatin plus paclitaxel (preferred for high-grade serous)

   • Carboplatin AUC 5-6 + paclitaxel 175 mg/m² every 3 weeks
   • 6 cycles are specifically recommended for high-grade serous carcinoma 1, 2

2. Carboplatin monotherapy

   • Carboplatin AUC 5-7
   • 6 cycles 1, 2

Duration Rationale

The most recent ESMO guidelines 1 explicitly state that high-grade serous carcinoma benefits from 6 cycles of chemotherapy, unlike other histologic subtypes where 3 cycles may suffice. This reflects the aggressive biology of high-grade serous disease. The 2019 ESMO-ESGO consensus 2 reinforces that "serous tumours should receive 6 cycles."

Evidence for Benefit

A population-based cohort study 3 of 223 optimally staged FIGO stage I high-grade serous ovarian cancer patients demonstrated:

• 5-year recurrence-free survival: 81% with chemotherapy vs 59% without
• 10-year overall survival: 78% with chemotherapy vs 62% without
• Multivariable hazard ratio for recurrence: 0.37 (95% CI 0.22-0.64, p<0.01)
• Multivariable hazard ratio for death: 0.50 (95% CI 0.28-0.89, p=0.02)

This real-world evidence strongly supports adjuvant chemotherapy even for completely staged IA disease.

Key Clinical Pitfalls

Do not withhold chemotherapy based on stage IA alone. The 2023 ESMO guidelines 1 clarify that while adjuvant chemotherapy may be optional for low-grade serous stage IA, this exception does NOT apply to high-grade serous carcinoma. High-grade histology is an independent adverse prognostic factor that overrides the favorable stage.

Ensure complete surgical staging. Approximately 60% of apparent early-stage ovarian cancers are upstaged after comprehensive surgical staging 1. Inadequate staging leads to undertreatment and worse outcomes.

Fertility preservation is generally not appropriate for high-grade serous carcinoma, even at stage IA, given the aggressive biology and bilateral disease risk. The guidelines 1 reserve fertility-sparing surgery for "favorable histology (i.e., low-grade tumours)."

Algorithm Summary

1. Confirm diagnosis: High-grade serous carcinoma, apparent stage IA
2. Complete surgical staging: As detailed above with lymphadenectomy
3. If truly stage IA after complete staging: Initiate adjuvant chemotherapy
4. Chemotherapy regimen: Carboplatin/paclitaxel × 6 cycles (preferred) OR carboplatin alone × 6 cycles
5. Surveillance: Per standard ovarian cancer follow-up protocols

The evidence consistently demonstrates that high-grade serous carcinoma requires systemic treatment regardless of early stage, with significant improvements in both recurrence-free and overall survival 3.